TY JOUR TI Variability of ionospheric ionization over Eurasia according to data from a high-latitude ionosonde chain during extreme magnetic storms in 2015 KW high-latitude ionosphere; ionosonde chain KW geomagnetic storm KW variations of ionospheric ionization JO Solnechno-Zemnaya Fizika AU Chernigovskaya, M.A. AU Setov, A.G. AU Ratovsky, K.G. AU Kalishin, A.S. AU Stepanov, A.E. PY 2024 IS 10 PB INFRA-M Academic Publishing LLC.